1. Field of the Invention
The present invention relates to a door shutter and, more particularly, to a door shutter to close a door automatically or to selectively locate the door to be open.
2. Description of Related Art
In most occasions, keeping a door closed is polite and also a safety concern. However, most people do not have this habit. Usually the door is open or swings in the wind. As leaving a door open not only raises home break-in concerns by an evildoer but also reduces the efficiency of an indoor air conditioning, manufacturers have developed many automatic hinges to resolve those problems. The automatic hinges drive the door to shut automatically after the door is open so that the door can be kept closed always and conveniently without paying attention by the users.
However, the conventional automatic hinge is attached between a door frame and a door and, thus, has to be prepared before the door is mounted to the frame so that the conventional automatic hinge can be built according to the structures of the door frame and door. Unfortunately, most present door assemblies are plain designs in door structure (i.e. only equipped with simple hinges) and do not have the automatic shutting efficiency. Therefore, the conventional automatic hinges can not be directly applied to the door assemblies (relative locations and distance between the door and the door frame are all factors to check whether the automatic hinges can be attached or not). When users apply the conventional automatic hinges to the door assemblies, the door must be detached, modified and reformed according to the door frame and the automatic hinges. Therefore, the attaching process of the conventional automatic hinge is complex and can not be accepted and performed by common users. The conventional automatic hinge is not widely utilized in households.
Other conventional automatic door shutters usually have pneumatic cylinders or hydraulic cylinders that greatly increase the cost and volume. Therefore, the conventional automatic door shutters are not accepted by general consumers and only limited to use in commercial sites or market buildings.